The Torpid State: Recent Advances in Metabolic Adaptations and Protective Mechanisms†

Frontiers in Physiology

Roberto F. Nespolo¹  Carlos Mejías¹  Samantha M. Logan²  Kenneth B. Storey²  Robert H. Henning³  Sylvain Giroud⁵  Jérémy Terrien⁶  Caroline Habold⁷ 

[1] Center of Applied Ecology and Sustainability, Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile;Department of Biology, Carleton University, Ottawa, ON, Canada;Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, Groningen, Netherlands;Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, ANID – Millennium Science Initiative Program-iBio, Valdivia, Chile;Research Institute of Wildlife Ecology, Department of Interdisciplinary Life Sciences, University of Veterinary Medicine, Vienna, Austria;Unité Mécanismes Adaptatifs et Evolution (MECADEV), UMR 7179, CNRS, Muséum National d’Histoire Naturelle, Brunoy, France;University of Strasbourg, CNRS, IPHC, UMR 7178, Strasbourg, France;

关键词: body temperature;    metabolic depression;    hibernation;    hormones;    lipids;    non-Holarctic heterotherms;   

DOI  :  10.3389/fphys.2020.623665

来源: DOAJ

【 摘 要 】

Torpor and hibernation are powerful strategies enabling animals to survive periods of low resource availability. The state of torpor results from an active and drastic reduction of an individual’s metabolic rate (MR) associated with a relatively pronounced decrease in body temperature. To date, several forms of torpor have been described in all three mammalian subclasses, i.e., monotremes, marsupials, and placentals, as well as in a few avian orders. This review highlights some of the characteristics, from the whole organism down to cellular and molecular aspects, associated with the torpor phenotype. The first part of this review focuses on the specific metabolic adaptations of torpor, as it is used by many species from temperate zones. This notably includes the endocrine changes involved in fat- and food-storing hibernating species, explaining biomedical implications of MR depression. We further compare adaptive mechanisms occurring in opportunistic vs. seasonal heterotherms, such as tropical and sub-tropical species. Such comparisons bring new insights into the metabolic origins of hibernation among tropical species, including resistance mechanisms to oxidative stress. The second section of this review emphasizes the mechanisms enabling heterotherms to protect their key organs against potential threats, such as reactive oxygen species, associated with the torpid state. We notably address the mechanisms of cellular rehabilitation and protection during torpor and hibernation, with an emphasis on the brain, a central organ requiring protection during torpor and recovery. Also, a special focus is given to the role of an ubiquitous and readily-diffusing molecule, hydrogen sulfide (H2S), in protecting against ischemia-reperfusion damage in various organs over the torpor-arousal cycle and during the torpid state. We conclude that (i) the flexibility of torpor use as an adaptive strategy enables different heterothermic species to substantially suppress their energy needs during periods of severely reduced food availability, (ii) the torpor phenotype implies marked metabolic adaptations from the whole organism down to cellular and molecular levels, and (iii) the torpid state is associated with highly efficient rehabilitation and protective mechanisms ensuring the continuity of proper bodily functions. Comparison of mechanisms in monotremes and marsupials is warranted for understanding the origin and evolution of mammalian torpor.

【 授权许可】

Unknown